President Barack Obama said that failures among US intelligence agencies to detect a Christmas Day plane plot were his responsibility, maintaining "the buck stops with me".

The president criticised agencies for failing to connect the dots and deduce that an attack was being planned in Yemen as he released a declassified version of an internal review.

But he said heads would not roll. "I am less interested in passing out blame than I am in learning from and correcting these mistakes to make us safer."

Taking the burden for the debacle for the first time in his fourth speech, he continued: "Ultimately the buck stops with me. As president, I have a solemn responsibility to protect our nation and our people. When the system fails, it is my responsibility."

Following criticism that his response to the attempted attack had been too tepid, the president took a more strident tone towards al-Qaeda, declaring: "We are at war, we are at war against al-Qaeda". "We will do whatever it takes to defeat them."

But he reiterated his appeal to the "vast majority of Muslims who reject al-Qaeda" to realise that terrorism offers "nothing except a bankrupt vision of misery and death - including the murder of fellow Muslims – while the United States stands with those who seek justice and progress".

Aides revealed that hundreds of air marshals will be diverted on to inbound flights to the United States amid fears that a dozen or more terrorists are preparing suicide missions.

Officials said intelligence reports and interviews with Umar Farouk Abdulmutallab, the Nigerian was accused of trying to detonate explosives on a flight to Detroit, suggested that other young men had been trained by groups linked to al-Qaeda.

Mr Obama was thought to have ordered almost all of the 3,200 existing air marshals, who are armed and work undercover, on to incoming US airliners by Feb 1. Officers from other law enforcement agencies would be called up to fill the gaps left on domestic flights.

"The rush is to get our people in place before they get theirs launched," said a senior law enforcement official.

"We have to strengthen the presence and capability of aviation law enforcement," said Janet Napolitano, head of homeland security.

The review ordered by the president immediately after the failed attack revealed that the US authorities knew that Abdulmutallab, who has been charged with trying to blow up Northwest Airlines flight 253, was a potential operative al-Qaeda operative. From his banker father, it was known that he was an extremist. It was also known that the al-Qaeda affiliate wanted to attack the United States.

Gen James Jones, the national security adviser, referring to the bomber, and the shootings at Fort Hood, Texas, in November by a Muslim army psychiatrist, said: "That's two strikes." He added that the president "certainly doesn't want that third strike, and neither does anybody else".

Homeland security officials said they had flagged Abdulmutallab as someone who should go through additional security screening upon landing. In a statement, the department said the alleged bomber's potential ties to extremists came up in a routine check of passengers en route to the US from overseas. Border agents were ready to question Abdulmutallab upon his arrival in Detroit.

Speculation has risen that Michael Leiter, the director of the National Counter Terrorism Centre, could be forced out after it was found that he went on a skiing holiday for several days after the attack. However it emerged yesterday that he had sought permission to do so from John Brennan, the president's counter-terrorism adviser.